1. Field of the Invention
The present invention relates to complex electronic devices, for example medical prosthesis systems.
2. Related Art
Complex electronic devices can incorporate many integrated circuits (ICs) which each provide different functionalities which cooperate to provide a working system.
Particular examples of complex electronic devices are complex medical devices, for example implantable hearing systems. An implantable hearing system typically consists of an external part and an internal part (i.e. the so-called implant). External and internal parts communicate with each other using a wireless link through the skin. Both internal and external parts can consist of one or multiple components, for example:                An external sound processor, capturing the microphone signal and conditioning the signal before sending it to the implant, is a typical component of the external part. Other external components could be a remote control, a programming interface, a diagnostics device, etc.;        The internal part typically has a stimulator component that is responsible for stimulating the auditory nerve. Internal components also can include an implantable battery, implantable microphone, a receiver for a wireless link, etc.        
Each of these components operates according to its own functional requirements. The cooperation of these individual functionalities provides a complex system which together provides the normal working operation of the system.
Continued developments in hearing devices are driven by market demands. Some demands relate to better signal processing to offer more hearing performance. Other demands include additional functionality to make the device more user friendly, for example an enhanced user interface, and connectivity to a PC or to wireless equipment.
When facing developments related to enhanced signal processing and functionality two challenging problems need to be resolved:                Miniaturization so that everything fits in as small a volume as possible, and        Low power consumption to achieve an acceptable battery life.        
It is proposed that both challenges can be met by including integrated circuits (ICs) in the system. Hence there is an expected future trend towards the incorporation of more ICs within the same system. Multiple ICs like microcontrollers or Digital Signal Processors (DSPs) (but also other ICs like wireless transceivers) are expected to be used more widely within the one implantable hearing system.
However, there are a number of disadvantages when using ICs for implantable hearing devices because they require a collective number of very specific functionalities that are not found in other devices on the market.
The specific functionalities for implantable hearing devices often require that custom-made ICs are used (i.e. application specific ICs or ASICs) and installed in the device during manufacture. Design, verification and qualification of such custom-made ICs for medical implantable devices is expensive and time-consuming. Therefore, to follow the trend of installing an increased number of custom-made ICs into a hearing device system results in a marked increase in the cost of manufacture.